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Why You Shouldn’t Use Recycled Concrete

In almost every other context, using recycled materials is something to be encouraged and praised. However, when it comes to concrete, the use of recycled concrete is not advised, and the team at iMix are going to explain why you should steer clear of repurposing the material.


If concrete is available to be repurposed, the likelihood is that it has been in use for many years as part of a different structure. New buildings are rarely demolished – it’s often old and unsightly tower blocks, or buildings that have been found to be unsafe. That means that any concrete available will have been exposed to the elements for many years.

Depending on the grade of the concrete, its strength may have lessened over the years, with compressive strength in recycled concrete found to decrease by 10-30%, which means that it might not be suitable or even safe to use in another project.


If concrete has been used before, its workability the second time round will be somewhat lacklustre. ‘Workability’ means the ease of pouring and placement of the concrete – if concrete has high workability, it can be poured and compacted easily, but if it has low workability, it’s going to be either difficult or impossible to pour it.

Water absorption

Recycled concrete is known to have an increased capacity for water absorption, too, ranging from 3% to 9%. Water might be a key component of the curing process, but excess moisture in concrete can spell a number of problems. The concrete will start to crack if there’s excess water present, which can weaken the material, as well as being unsightly. It can also make the concrete expand, which can lead to something known as ‘popouts’ – cone shaped fragments which break out from the surface of the concrete.

Lack of guidelines

For fresh concrete, there are countless rules and regulations that need to be followed in order to ensure the mix is safe and ready for use. However, with recycled concrete, such regulations are more sparse, which means it can be difficult to fully ascertain or corroborate the quality of the mixture. If you’re using a weak or unsafe mixture for your structure, you risk issues further down the line.

As you can see, there are several reasons why the use of recycled concrete and aggregates can cause problems for a construction project. Despite the act of recycling being beneficial for our environment, when it comes to concrete, the potential negatives outweigh the positives.

iMix are proud to provide the highest quality concrete, made to order, for domestic and commercial customers throughout London and surrounding areas. For more information about what we do, get in touch with us today on 0800 030 9015  or fill in our handy contact form and we’ll be happy to help.

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